package com.hmdp.service.impl;

import cn.hutool.core.bean.BeanUtil;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.dto.Result;
import com.hmdp.entity.VoucherOrder;
import com.hmdp.mapper.VoucherOrderMapper;
import com.hmdp.service.ISeckillVoucherService;
import com.hmdp.service.IVoucherOrderService;
import com.hmdp.utils.RedisIdWorker;
import com.hmdp.utils.UserHolder;
import lombok.extern.slf4j.Slf4j;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.aop.framework.AopContext;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.connection.stream.*;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.PostConstruct;
import javax.annotation.Resource;
import java.time.Duration;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
@Slf4j
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {


    @Autowired
    private ISeckillVoucherService seckillVoucherService;

    @Resource
    private RedisIdWorker redisIdWorker;

    @Resource
    private StringRedisTemplate stringRedisTemplate;

    @Resource
    private RedissonClient redissonClient;

    private static final DefaultRedisScript<Long> SECKILL_SCRIPT;

    static {
        SECKILL_SCRIPT = new DefaultRedisScript<>();
        SECKILL_SCRIPT.setLocation(new ClassPathResource("seckill.lua"));
        SECKILL_SCRIPT.setResultType(Long.class);
    }

    private IVoucherOrderService proxy = null;


    private ExecutorService SECKILL_ORDER_EXECUTOR = Executors.newSingleThreadExecutor();

    @PostConstruct // 当前类初始化完毕时就会执行的方法
    private void init() {
        SECKILL_ORDER_EXECUTOR.submit(new VoucherOrderHandler());
    }

    /* private BlockingQueue<VoucherOrder> orderTasks = new ArrayBlockingQueue<>(1024 * 1024);
     private class VoucherOrderHandler implements Runnable {

         @Override
         public void run() {
             while (true) {
                 try {
                     // 1 获取队列中的订单信息
                     //没有消息，就会阻塞等待...
                     VoucherOrder voucherOrder = orderTasks.take();
                     // 2 创建订单
                     handleVoucherOrder(voucherOrder);
                 } catch (Exception e) {
                     log.error("处理订单异常 {}", e.getMessage());
                 }
             }
         }
     }*/
    private class VoucherOrderHandler implements Runnable {

        private String queueName = "stream.orders";

        @Override
        public void run() {
            while (true) {
                try {
                    // 1 获取redis消息队列中的订单信息
                    List<MapRecord<String, Object, Object>> list = stringRedisTemplate.opsForStream().read(
                            Consumer.from("g1", "c1"),
                            StreamReadOptions.empty().count(1).block(Duration.ofSeconds(2)),
                            StreamOffset.create(queueName, ReadOffset.lastConsumed())
                    );
                    // 2 判断消息是否获取成功
                    if (list == null || list.isEmpty()) {
                        // 2.1 如果获取失败，说明没有消息，继续下一次循环
                        continue;
                    }
                    // 3 解析消息中的订单
                    MapRecord<String, Object, Object> record = list.get(0);
                    Map<Object, Object> values = record.getValue();
                    VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(values, new VoucherOrder(), true);
                    // 4 如果获取成功，可以下单
                    handleVoucherOrder(voucherOrder);
                    // 5 ACK确认
                    stringRedisTemplate.opsForStream().acknowledge(
                            queueName,
                            "g1",
                            record.getId()
                    );
                } catch (Exception e) {
                    log.error("处理订单异常 {}", e.getMessage());
                    handlePendingList();
                }
            }
        }

        private void handlePendingList() {
            while (true) {
                try {
                    // 1 获取redis消息队列pending-list中的订单信息
                    List<MapRecord<String, Object, Object>> list = stringRedisTemplate.opsForStream().read(
                            Consumer.from("g1", "c1"),
                            StreamReadOptions.empty().count(1),
                            StreamOffset.create(queueName, ReadOffset.from("0"))
                    );
                    // 2 判断消息是否获取成功
                    if (list == null || list.isEmpty()) {
                        // 2.1 如果获取失败，说明pending-list没有消息，结束循环
                        break;
                    }
                    // 3 解析消息中的订单
                    MapRecord<String, Object, Object> record = list.get(0);
                    Map<Object, Object> values = record.getValue();
                    VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(values, new VoucherOrder(), true);
                    // 4 如果获取成功，可以下单
                    handleVoucherOrder(voucherOrder);
                    // 5 ACK确认
                    stringRedisTemplate.opsForStream().acknowledge(
                            queueName,
                            "g1",
                            record.getId()
                    );
                } catch (Exception e) {
                    log.error("处理pending-list异常 {}", e.getMessage());
                    try {
                        Thread.sleep(20);
                    } catch (InterruptedException ex) {
                        ex.printStackTrace();
                    }
                }
            }
        }
    }

    private void handleVoucherOrder(VoucherOrder voucherOrder) {
        Long userId = voucherOrder.getUserId();
        //利用redisson分布式锁实现高并发下的一人一单功能
        //获取锁对象
        RLock redisLock = redissonClient.getLock("lock:order:" + userId);
        boolean isLock = redisLock.tryLock();
        if (!isLock) {
            //获取锁失败，返回错误或重试
            log.error("不允许重复下单");
            return;
        }
        try {
            proxy.createVocherOrder(voucherOrder);
        } finally {
            redisLock.unlock();
        }
    }

    /**
     * 使用Lua脚本异步实现一人一单的优惠券秒杀业务
     *
     * @param voucherId
     */
    @Override
    public Result seckillVoucher(Long voucherId) {
        Long userId = UserHolder.getUser().getId();
        //获取订单id
        long orderId = redisIdWorker.nextId("order");
        // 1 执行lua脚本
        Long result = stringRedisTemplate.execute(
                SECKILL_SCRIPT,
                Collections.emptyList(),
                voucherId.toString(),
                userId.toString(),
                String.valueOf(orderId));
        // 2 判断结果是否是0
        int r = result.intValue();
        if (r != 0) {
            // 2.1 不是0，代表没有购买资格
            return Result.fail(r == 1 ? "库存不足" : "不能重复下单");
        }
        // 3 获取代理对象
        //用当前对象的代理对象调用方法，事务才能生效，不能用this来调用方法
        proxy = (IVoucherOrderService) AopContext.currentProxy();
        // 4 返回订单id
        return Result.ok(orderId);
    }

    /* *//**
     * 使用Lua脚本异步实现一人一单的优惠券秒杀业务
     *
     * @param voucherId
     *//*
    @Override
    public Result seckillVoucher(Long voucherId) {
        Long userId = UserHolder.getUser().getId();
        // 1 执行lua脚本
        Long result = stringRedisTemplate.execute(
                SECKILL_SCRIPT,
                Collections.emptyList(),
                voucherId.toString(),
                userId.toString());
        // 2 判断结果是否是0
        int r = result.intValue();
        if (r != 0) {
            // 2.1 不是0，代表没有购买资格
            return Result.fail(r == 1 ? "库存不足" : "不能重复下单");
        }
        // 2.2 为0，有购买资格，把下单信息保存到阻塞队列中
        long orderId = redisIdWorker.nextId("order");

        VoucherOrder order = new VoucherOrder();
        order.setId(redisIdWorker.nextId("order"));
        order.setVoucherId(voucherId);
        order.setUserId(userId);
        // 3 保存到阻塞队列
        orderTasks.add(order);
        // 4 获取代理对象
        //用当前对象的代理对象调用方法，事务才能生效，不能用this来调用方法
        proxy = (IVoucherOrderService) AopContext.currentProxy();
        // 5 返回订单id
        return Result.ok(orderId);
    }*/


    /*@Override
    public Result seckillVoucher(Long voucherId) {

        //1 查询优惠券
        SeckillVoucher voucher = seckillVoucherService.getById(voucherId);
        if (voucher == null) {
            return Result.fail("优惠券不存在");
        }
        //2 判断秒杀是否开始
        if (voucher.getBeginTime().isAfter(LocalDateTime.now())) {
            //尚未开始
            return Result.fail("秒杀活动尚未开始");
        }
        //3 判断秒杀是否结束
        if (voucher.getEndTime().isBefore(LocalDateTime.now())) {
            //已经结束
            return Result.fail("秒杀活动已经结束");
        }
        //4 判断库存是否充足
        if (voucher.getStock() < 1) {
            return Result.fail("秒杀券库存不足");
        }
        //给userId加锁
        Long userId = UserHolder.getUser().getId();
        //自定义分布式锁实现高并发下的一人一单功能
//        SimpleRedisLock redisLock = new SimpleRedisLock("lock:order:" + userId, stringRedisTemplate);
        //利用redisson分布式锁实现高并发下的一人一单功能
        RLock redisLock = redissonClient.getLock("lock:order:" + userId);
        boolean isLock = redisLock.tryLock();
        if (!isLock) {
            //获取锁失败，返回错误或重试
            return Result.fail("不允许重复下单");
        }
        try {
            //用当前对象的代理对象调用方法，事务才能生效，不能用this来调用方法
            IVoucherOrderService proxy = (IVoucherOrderService) AopContext.currentProxy();
            return proxy.createVocherOrder(voucherId);
        } finally {
            redisLock.unlock();
        }
    }*/

    /**
     * 一人一单
     *
     * @return
     */
    @Transactional
    public void createVocherOrder(VoucherOrder voucherOrder) {
        //查询该用户是否已经秒杀了优惠券
        Long userId = voucherOrder.getUserId();
        Long count = query().eq("user_id", userId)
                .eq("voucher_id", voucherOrder.getVoucherId()).count();
        if (count > 0) {
            //该用户已下过单
            log.error("该用户已经购买过此优惠券");
            return;
        }
        //5 扣减库存
        boolean success = seckillVoucherService.update()
                .setSql("stock = stock - 1")
                .eq("voucher_id", voucherOrder.getVoucherId())
                //乐观锁解决超卖
                .gt("stock", 0)
                .update();
        if (!success) {
            log.error("秒杀券库存不足");
            return;
        }
        //创建订单
        this.save(voucherOrder);
    }

    /**
     * 一人一单
     *
     * @param voucherId
     * @return
     */
   /* @Transactional
    public Result createVocherOrder(Long voucherId) {
        //查询该用户是否已经秒杀了优惠券
        Long userId = UserHolder.getUser().getId();
        Long count = query().eq("user_id", userId).eq("voucher_id", voucherId).count();
        if (count > 0) {
            //该用户已下过单
            return Result.fail("该用户已经购买过此优惠券");
        }
        //5 扣减库存
        boolean success = seckillVoucherService.update()
                .setSql("stock = stock - 1")
                .eq("voucher_id", voucherId)
                //乐观锁解决超卖
                .gt("stock", 0)
                .update();
        if (!success) {
            return Result.fail("秒杀券库存不足");
        }
        //6 创建订单
        VoucherOrder order = new VoucherOrder();
        order.setId(redisIdWorker.nextId("order"));
        order.setVoucherId(voucherId);
        order.setUserId(userId);
        this.save(order);
        //返回订单id
        return Result.ok(order.getId());
    }*/
}
